Katrina Hobbs, 25, has terminal cancer but is determined to fulfil the motherly role of counselling her three-year-old daughter through everything that the journey to womanhood can throw up.

Her response has been to prepare a “legacy of advice” to guide Ella during the ups and downs.

There are cards for Ella’s birthdays; notes of congratulation on passing her exams, on her engagement, her marriage, her first home, a newborn baby boy or girl; and even advice on dealing with bullies. Five-minute video messages have been recorded for each birthday.

“I know that when she is older she will face tough times and will have problems,” said Mrs Hobbs, of Bridgwater, Somerset. “I know that I might not be there to protect her. That is really hard for me.

“She might be stressed, or questioning herself, or her sexuality, for example when she’s a teenager, so I’ve written to tell her not to worry if she’s feeling confused, that it’s natural and she will be OK.

“If she gets bullied I’ve written to say that it is probably because she is unique, and that she should celebrate that because it’s what makes her special.”

Mrs Hobbs, a carer for the elderly, is one of only four people in the world known to be suffering from Alveolar Soft Part Sarcoma and has more than 12 tumours in her lungs. Doctors are unable to predict how long she will live. She has made arrangements for her daughter to be handed the cards and advice when appropriate. “Ella is such an amazing girl,” said Mrs Hobbs. “She has such a big personality. She says to me 'We are best friends, mummy, and we will be forever’.

“When I am having a bad day I try not to let it show but she knows and she says 'it’s OK, I’m here’.” Mrs Hobbs said she had “tried to do something memorable” for her daughter every day. “It is something I feel will help her feel that I am always around. I want her to know that I had already thought of her future before she was thinking about it,” she added.

Mrs Hobbs first noticed a lump on her left buttock in 2008 and was diagnosed with Alveolar Soft Part Sarcoma later that year. There is no cure or treatment, although she is taking part in trials of a kidney cancer drug which could help stop the growth of the tumours.

Mrs Hobbs was three months pregnant with her second child when she was diagnosed. Doctors had to deliver the boy, named Ashton, at 20 weeks so she could be treated, but he did not survive.

“They said there was no guarantee that either I or the baby would survive if I didn’t have treatment,” said Mrs Hobbs.

“The loss of my child was harder to deal with than the cancer itself.”

Mrs Hobbs and her husband, who has asked not to be named, separated 15 months ago but are trying to re-establish their relationship.

She said she had not told her daughter that her cancer was terminal.

“She knows that some people can’t find a medicine that works and they pass away. She’s adapted very well and I’m really proud of her.”

Mrs Hobbs is writing a book dedicated to her daughter about her experience.